Photosystem II in Symbiotic Algae

1976 ◽  
Vol 3 (1) ◽  
pp. 133 ◽  
Author(s):  
RM Smillie
Keyword(s):  
Red Light ◽  
Pocillopora Damicornis ◽  
C3 Plant ◽  
Symbiotic Algae ◽  
Symbiodinium Microadriaticum ◽  
Unknown Species ◽  
Lizard Island ◽  
Tridacna Maxima ◽  
Photosynthetic Potential ◽  
Gymnodinium Microadriaticum

Symbiotic brown algae (zooxanthellae), Gymnodinium microadriaticum (= Symbiodinium microadriaticum), were isolated from the coral polyp Pocillopora damicornis and from the mantle of the clam Hippopus hippopus collected from coral reefs near Lizard Island on the Great Barrier Reef. Passage of the coral and clam zooxanthellae through a Yeda Press at 2000 and 21 000 p.s.i., respectively, yielded preparations of chloroplast lamellae with the ratio of chlorophyll α to chlorophyll c ranging from 0.95 to 1.2. The chloroplast preparations photoreduced 2,6-dichlorophenolindophenol (DCPIP) at rates of 1.66 (coral zooxanthellae chloroplasts) and 1.96 (clam zooxanthellae chloroplasts) micromoles DCPIP reduced per minute per milligram total chlorophyll in white light. Rates were 30-50% lower in red light. The photoreduction was inhibited more than 99% by 2.5 μM 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Comparisons made with maize chloroplasts indicated that the clam zooxanthellae chloroplasts required only slightly higher light intensities for maximum rates of photoreduction of DCPIP than the grana-containing maize mesophyll chloroplasts. The coral zooxanthellae chloroplasts required a still higher light intensity for near saturation of the photoreduction of DCPIP, but not as high as that required by maize bundle sheath chloroplasts. Chloroplasts prepared from green algae isolated from the tissues of a tunicate of unknown species also photoreduced DCPIP but at low rates. Light saturation for the reaction was attained at around the same intensity as for the clam zooxanthellae chloroplasts. Based on the photosynthetic rate of zooxanthellae isolated from the clam Tridacna maxima and the number of cells contained in the mantle, it was concluded that the photosynthetic potential of the mantle of T. maxima, on either a chlorophyll or area basis, was about the same as that of a leaf of a C3 plant.

scholarly journals Rapid Recruitment of Symbiotic Algae into Developing Scleractinian Coral Tissues

2019 ◽  
Vol 7 (9) ◽  
pp. 306
Author(s):  
Bockel ◽  
Rinkevich
Keyword(s):  
Tissue Expansion ◽  
Outer Edge ◽  
Tissue Growth ◽  
Coral Tissue ◽  
Coral Host ◽  
Pocillopora Damicornis ◽  
Stylophora Pistillata ◽  
Symbiotic Algae ◽  
Glass Slides ◽  
Host Tissues

While the early acquisition of Symbiodiniaceae algae into coral host tissues has been extensively studied, the dynamics of the migration of algal cells into rapidly expanding coral tissues still lacks a systematic study. This work examined two Red Sea branching coral species, Pocillopora damicornis and Stylophora pistillata, as they were growing and expanding their tissue laterally on glass slides (January–June, 2014; 450 assays; five colonies/species). We measured lateral tissue expansion rates and intratissue dinoflagellate migration rates. Tissue growth rates significantly differed between the two species (with Stylophora faster than Pocillopora), but not between genotypes within a species. Using a “flow-through coral chamber” under the microscope, the migration of dinoflagellates towards the peripheral edges of the expanding coral tissue was quantified. On a five-day timescale, the density of the endosymbiotic dinoflagellate cells, presenting within a 90 µm region of expanding coral tissue (outer edge), increased by a factor of 23.6 for Pocillopora (from 1.2 × 104 cells cm‒² to 2.4 × 105 cells cm‒²) and by a factor of 6.8 for Stylophora (from 3.6 × 104 cells cm‒² to 2.4 × 105 cells cm‒²). The infection rates were fast (5.2 × 104 and 4.1 × 104 algal cells day-1 cm‒², respectively), further providing evidence of an as yet unknown pathway of algal movement within coral host tissues.

scholarly journals Identifying conserved molecular mechanisms of thermo-acclimation in symbiotic organisms

2018 ◽  
Author(s):  
Homere J. Alves Monteiro ◽  
Chloe Brahmi ◽  
Anderson Blair Mayfield ◽  
Jeremie Vidal-Dupiol ◽  
Bruno Lapeyre ◽  
...  
Keyword(s):  
High Temperatures ◽  
Molecular Mechanisms ◽  
Seawater Temperature ◽  
French Polynesia ◽  
Giant Clam ◽  
Pocillopora Damicornis ◽  
Free Living ◽  
Module Preservation ◽  
Tridacna Maxima ◽  
Symbiotic Organisms

Seawater temperature rise in French Polynesia has repeatedly resulted in symbiosis breakdown between giant clam (Tridacna maxima) and dinoflagellates (Symbiodinium spp.), particularly in small individuals. Herein, we explored the physiological and gene expression responses of the clam hosts and their photosynthetically active symbionts over a 65-day experiment in which clams were exposed to either normal or environmentally relevant elevated seawater temperatures. These data were combined with publicly available data for both free-living Symbiodinium (clades C1 and F) and Symbiodinium spp. in hospite with the coral Pocillopora damicornis. Gene module preservation analysis revealed that the function of the symbionts' photosystem II was impaired at high temperatures, and this response was conserved across all holobionts and Symbiodinium clades examined. Similarly, activation of the phytohormone abscisic acid signaling and epigenetics modulation appeared to be a key response mechanisms for symbionts in hospite with giant clams exposed to high temperatures and also distinguish thermo-tolerant from thermo-sensitive Symbiodinium C1 phenotypes.

scholarly journals Differential Affinities of a Pocillopora damicornis Galectin to Five Genera of Symbiodiniaceae at Different Temperatures

2021 ◽  
Vol 8 ◽  
Author(s):  
Xingjuan Wang ◽  
Zhongjie Wu ◽  
Yibo Wu ◽  
Mingxun An ◽  
Zhi Zhou ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Cell Surface ◽  
Binding Affinity ◽  
Molecular Basis ◽  
Binding Affinities ◽  
Pocillopora Damicornis ◽  
Coral Reef Ecosystem ◽  
Symbiodinium Microadriaticum ◽  
Different Temperatures ◽  
Reef Ecosystem

The symbiosis of coral-Symbiodiniaceae is the quintessential basis of the coral reef ecosystem, and its breakdown results in coral bleaching, one of the most severe ecological catastrophes in the ocean. Critical to the establishment of the symbiosis is the host’s specific recognition of the symbionts through the binding of the coral host’s pattern recognition receptors (PRRs) to the symbiont cell surface’s glycoconjugates. However, the molecular basis for this recognition process is poorly understood. The present study investigated the binding affinities of the coral galectin PdGLT-1 to different symbiodiniacean species under different temperatures. At 25°C, the PdGLT-1 recombinant protein (rPdGLT-1) exhibited different binding affinities to different symbiodiniacean species from five genera, with a significantly higher binding affinity (p < 0.05) to Fugacium kawagutii (2.6-fold) and Cladocopium goreaui (1.9-fold) than Symbiodinium microadriaticum. The binding topology of rPdGLT-1 differed among the five symbiodiniacean species; for S. microadriaticum, Breviolum minutum, and Durusdinium trenchii, the binding was on some specific sites on the cell surface, whereas for C. goreaui and F. kawagutii, the binding signals were detected over the whole cell surface. Interestingly, PdGLT-1 binding induced agglutination of F. kawagutii cells but not of C. goreaui, explaining why C. goreaui was the most dominant symbiodiniacean symbionts in corals. Moreover, the affinity of rPdGLT-1 to Symbiodiniaceae was affected by temperature, and the highest binding affinities were observed at 30, 20, 30, 35, and 30°C for S. microadriaticum, B. minutum, C. goreaui, D. trenchii, and F. kawagutii, respectively. The optimal binding temperatures were consistent with the current understanding that D. trenchii was the most thermal resistant among these species. These results suggest that the binding affinity of the PRR PdGLT-1 may determine the specificity of host-symbiont pairing and explain why Cladocopium is the dominant symbionts of coral P. damicornis at normal temperature, and corals with Durusdinium symbionts may survive better at high temperature.

Ultrastructure and Lipid Composition of Zooxanthellae from Tridacna maxima

1976 ◽  
Vol 3 (1) ◽  
pp. 33 ◽  
Author(s):  
DG Bishop ◽  
JM Bain ◽  
WJS Downton
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Linolenic Acid ◽  
Lipid Composition ◽  
Host Tissue ◽  
Plant Lipids ◽  
Tridacna Maxima ◽  
Gymnodinium Microadriaticum ◽  
Clam Tissue

Isolation of zooxanthellae (Gymnodinium microadriaticum) from clam tissue does not result in any loss of the outer limiting layers and the ultrastructure of the cell is similar to that of zooxanthellae found in other clams and corals. The major lipid components of G. microadriaticum are galactosyldiacylglycerols which comprise about 50% of the extractable lipid. The major fatty acids present are palmitic, γ-linolenic and octadecatetraenoic acids, together with a component identified as octadecapentaenoic acid. The presence of γ-linolenic acid is more representative of animal lipids than of plant lipids and there is a possibility that growth of the zooxanthella in a host tissue can affect the fatty acid composition.

The identity of two species of cyphonautes larvae (Bryozoa: Cheilostomata) from Lizard Island, Great Barrier Reef, Australia

2001 ◽  
Vol 81 (6) ◽  
pp. 995-999 ◽  
Author(s):  
P.J. Hayward
Keyword(s):  
Great Barrier Reef ◽  
The Other ◽  
Shallow Waters ◽  
Barrier Reef ◽  
Unknown Species ◽  
Lizard Island

Two species of bryozoan cyphonautes larvae are described and illustrated from plankton tows made among coral heads in shallow waters at Lizard Island, Great Barrier Reef, Australia. Individuals of both species settled and metamorphosed, and their ancestrulae and early astogeny are also described and illustrated. One is recognized as a formerly unknown species of Conopeum, C. ponticum sp. nov., the other is attributed to Biflustra reticulata.

scholarly journals Probing the Structural Basis of Citrus Phytochrome B using Computational Modelling and Molecular Dynamics Simulation Approaches

2021 ◽  
Author(s):  
Muhammad Tahir ul Qamar ◽  
Muhammad Usman Mirza ◽  
Jia-Ming Song ◽  
Muhammad Junaid Rao ◽  
Xi-Tong Zhu ◽  
...  
Keyword(s):  
Md Simulation ◽  
Red Light ◽  
3D Structure ◽  
Computational Modelling ◽  
Structural Difference ◽  
Dynamics Simulation ◽  
Structural Basis ◽  
Functional Implications ◽  
Domain Organisation ◽  
Photosynthetic Potential

Phytochromes are known as red/far-red light photoreceptors and responsible for directing the photosensory responses across the species. Such responses majorly include photosynthetic potential and pigmentation in bacteria, whereas in a plant, they are involved in chloroplast development and photomorphogenesis. Many prokaryotic Phys have been modelled for their structural/functional analysis, but their plant counterparts have not been explored yet. To date, only the crystal structures of the photo-sensing module of PhyB isoform from Arabidopsis and Glycine have been resolved experimentally. Thus, in this study, we elucidated the complete 3D structure of Citrus PhyB. Initially, the structure and organisation of the Citrus PhyB have been predicted computationally, which were found to have the same domain organisation as A.thaliana and G.max PhyBs, yet their considerable distinct structural difference indicated potential divergence in signaling/functioning. Therefore, to evaluate the structural and functional implications of Citrus PhyB, we compared its structure with A. thaliana and G. max PhyBs using MD simulation. The modeling studies revealed that the region of Citrus PhyB-GAF domain possibly contributes to the variations. Hence, structural/molecular insights into Citrus PhyB can help to discover the Phys signaling and thus, an essential framework can be designed for optogenetic reagents and various agricultural benefits.

Effects of cyanide on corals in relation to cyanide fishing on reefs

1997 ◽  
Vol 48 (6) ◽  
pp. 517 ◽  
Author(s):  
Ross J. Jones ◽  
Andrew L. Steven
Keyword(s):  
Sea Water ◽  
Pocillopora Damicornis ◽  
Symbiotic Algae ◽  
Exposure Levels ◽  
Fishing Practices ◽  
Zooxanthellate Corals

Small fragments of the zooxanthellate corals Pocillopora damicornis and Porites lichen were subjected to a range of cyanide concentrations for various times (i.e. to various cyanide doses). Doses encompassed those likely to be experienced by corals as a result of various cyanide fishing practices. Following the highest doses, corals died; after medium doses, they lost their zooxanthellae (symbiotic algae) resulting in a discolouration or ‘bleaching’; and after the lowest doses they lost zooxanthellae but not in sufficient numbers to cause noticeable discolouration. Respiratory rates of P. damicornis were inhibited by 10–90% following exposure to cyanide but recovered to pre-exposure levels within 1–2 h after transfer to clean sea water.

scholarly journals Experimental Bleaching of a Reef-Building Coral Using a Simplified Recirculating Laboratory Exposure System

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Mace G. Barron ◽  
Cheryl J. McGill ◽  
Lee A. Courtney ◽  
Dragoslav T. Marcovich
Keyword(s):  
Solar Radiation ◽  
Tissue Loss ◽  
Pocillopora Damicornis ◽  
Critical Research ◽  
Solar Simulator ◽  
Exposure System ◽  
Symbiotic Algae ◽  
Coral Reef Ecosystems ◽  
Radiation Treatments ◽  
Laboratory Exposure

Determining stressor-response relationships in reef building corals continues to be a critical research need due to global declines in coral reef ecosystems and projected declines for the future. A simplified recirculating coral exposure system was coupled to a solar simulator to allow laboratory testing of a diversity of species and morphologies of reef building corals under ecologically relevant conditions of temperature and solar radiation. Combinations of lamps and attenuating filters allowed for assignment of solar radiation treatments in experimental bleaching studies. Three bleaching experiments were performed using the reef building coral,Pocillopora damicornis, to assess the reproducibility of system performance and coral responses under control and stress conditions. Experiments showed consistent temperature- and solar radiation dependent-changes in pigment, numbers of symbiotic algae, photosystem II quantum yield, and tissue loss during exposure and recovery. The laboratory exposure system is recommended for use in experimental bleaching studies with reef building corals.

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